<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <script src="https://cdn.bootcss.com/jquery/1.11.3/jquery.js"></script>
    <title>Title</title>
</head>
<body>
<div id="test">click</div>
<script>
    var paylist = [
        {"id":"1","paymode": '1', "payname": "现金", "paymoney": "20"}
        , {"id":"3","paymode": '2', "payname": "支付宝", "paymoney": "50"}
        , {"id":"2","paymode": '1', "payname": "现金", "paymoney": "40"}
    ];

    //去重
    var newPaylist = uniqueArray(paylist,'payname');

    //形成新结构
    $("#test").html("");
    $.each(newPaylist,function(index,item){
        var html = '';
        html += '<span>'+item.payname+'</span><br/>';
        $("#test").append(html);
    });

    /*
     * JSON数组去重
     * @param: [array] json Array
     * @param: [string] 唯一的key名，根据此键名进行去重
     */
    function uniqueArray(array, key) {
        var result = [array[0]];
        for (var i = 1; i < array.length; i++) {
            var item = array[i];
            var repeat = false;
            for (var j = 0; j < result.length; j++) {
                if (item[key] == result[j][key]) {
                    repeat = true;
                    break;
                }
            }
            if (!repeat) {
                result.push(item);
            }
        }
        return result;
    }
</script>
</body>
</html>